refactor: Refactor StatisticalEvaluator

[silvanocerza]

Related Issues

• Part of Unify evaluation API of model-based and statistical metrics #6903

Proposed Changes:

Remove preprocessing in StatisticalEvaluator as we're going to use the TextCleaner component from #6997.

Move labels from __init__ to run.

How did you test it?

I updated unit tests.

Notes for the reviewer

This stems from feedback received in PR #6980.

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 7918003446

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 20 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.1%) to 89.172%

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Files with Coverage Reduction	New Missed Lines	%
components/eval/statistical_evaluator.py	3	95.0%
components/eval/sas_evaluator.py	17	63.16%

Totals
Change from base Build 7904082418:	0.1%
Covered Lines:	4941
Relevant Lines:	5541

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💛 - Coveralls

[shadeMe]

LGTM; just some minor changes. Feel free to merge once you're done.